Semiconductor devices are fragile and typically assembled in a package to protect the device from damage due to thermal and mechanical stress, corrosion, contamination, and etc. Semiconductor packaging typically includes heat dissipation components such as heat dissipation layers, heat spreaders and/or heat sinks.
Laser diodes are a type of semiconductor device. In gallium arsenide (GaAs) and indium phosphide (InP) based laser packages, the lasers grown on GaAs and InP are bonded onto CTE-matched submounts to dissipate heat. Such submounts are typically made of aluminum nitride (AlN), and/or beryllium oxide (BeO). However, these materials have poorer thermal conductivity compared to silicon carbide (SiC), copper (Cu), cubic boron nitride (c-BN), graphite, graphene, graphene-composites, carbon nanotubes, carbon nanotube composites, diamond and encapsulated pyrolytic graphite. Use of aforementioned higher thermal conductivity materials have distinct performance advantages; however, CTE-mismatched submounts may lead to compromise in reliability of semiconductor devices.
In order to take advantage of the higher thermal conductivity of materials such as SiC, Cu, cubic BN, graphite, graphene, diamond and encapsulated pyrolytic graphite pairing of a CTE mis-matched heat spreader with a heat source such as a semiconductor device may require additional measures to reduce transfer of mechanical stress from the highly thermally conductive material to the heat source due to the CTE mis-match. Such measures may be unreliable and the time and cost of implementing measures to reduce mechanical stress may be prohibitive.